Grillstone



FIG. 1 is a top perspective view of the grillstone showing my new design;

FIG. 2 is a side elevation view thereof;

FIG. 3 is an top elevation view thereof viewed from the top of FIG. 1;

FIG. 4 is an end elevation view thereof viewed from either the left or the right end of FIG. 1; and,

FIG. 5 is a bottom elevation view thereof. 

The ornamental design for a grillstone, as shown and described. 